The Merrill Lock and Dam was the second in a series of ten locks and dams built along the Ohio River between 1892 and 1904. The isolated grouping was designed by and named for engineer William E. Merrill, supervisor of the Ohio River improvement, assisted by engineer William H. Chadbourn Jr. The complex, replaced in 1936 by the Montgomery Lock and Dam, has survived several owners and uses, most recently as a restaurant and marina. The orange-colored brick buildings perch on a narrow strip of land parallel to the Ohio River (29.5 miles northwest of Pittsburgh). The lockhouse's round-arched apertures and tower with flared and bracketed eaves lend it an Italianate flavor. The tower originally concealed a water tank for the lock buildings, and a semicircular bay at its base offers views up and down the river. Stone detailing at the imposts and sills sets off the patterned brick, while a large five-bay, hipped-roof dormer on the river facade and a smaller version facing east complement the height of the tower and chimney. An oversized paneled chimney anchors the rear elevation with the coal storage area at its base. The interior formerly housed the machinery used to operate the lock gates, and retains a foliated metal stair rail to the south of the main entrance.

To the east of the lockhouse, a foursquare house, tied stylistically to the main building through the use of round-arched windows on the upper story, housed either the lockmaster's family or crews. An identical house west of the lockhouse was demolished.